Discs for the mercury unshorter switch



Dec. 29, 1964 H. s. KALISH ETAL DISCS FOR THE MERCURY UNSHORTER SWITCH Filed Nov. 22, 1952 Fig.2

INVENTORS HERBERTS. KAL/SH JOl-l/VG/LBERT RAY, JR.

United States Patent Ofiiice 3,163,726 Patented Dec. 29, 19:64

DISCS FOR THE MnRbURY UNSHORTER swrrcn Herbert S. Kalish, Jackson Heights, and John Gilbert Ray,

Mineola, N.Y., assiguors, by mesne assignments, to

Sylvania Electric Products Inc., Wilmington, Del., a

corporation of Delaware Filed Nov. 22, 1952, Ser. No. 322,052 6 Claims. (Cl. 2Gll- 32) This invention relates to a timing switch. More particularly, it relates to an unshorter switch of the type in which an interval of time is measured by the speed with which a conducting fluid passes from one chamber of the switch to another during the period in which a switch is caused to revolve about an axis.

A great many switches have been developed for this purpose, the most common of which consists of a receptacle containing two chambers divided by a porous membrane through which the conducting medium is forced during the rotation of the switch. The porous membrane in the prior art switches have heretofore consisted of such things as paper or even compressed metallic powders in the form of a thin porous member. Although for some cases such switches have produced the results desired the membranes used have for the most part either become gummed up and prevented the flow of conducting medium therethrough or have not been suillciently impervious to allow for the storage and transportation of the switches under normal operating conditions without adversely affecting the timing properties of the switch. This latter adverse effect is produced by the passage of medium through the diaphragm when the switch is jolted and jumbled. Furthermore, the switches of the prior art could only be successfully used for single purposes, that is to say, to give the desired lapse of time interval at a certain specified spinning rate of the switch.

It is an object of this invention to develop a timing switch which can withstand severe jolts and jumbling without interfering deleteriously with its timing charactertistcs.

It is a further object of this invention to develop an improved timing switch which can be used for a dual purpose.

It is a still further object of this invention to develop a switch of improved quality and design.

In accordance with this invention it has been found that these objects and other advantages incidental thereto can be obained by replacing the porous barrier separating the two chambers with a double porous disc arrangement in which the one disc is spaced from the other by no more than .030".

In the drawings which illustrate embodiments of this invention FIGURE 1 is a front elevation partly in section of a double disc switch assembly.

FIGURE 2 is a sectional view of a second type of a double disc suitable for use in a switch of this type.

FIGURE 3 is a third type of double disc suitable for use in the switch assembly of FIGURE 1.

The preferred type unshorter switch illustrated in FIGURE 1 of the drawing has two main chambers ill and 12 separated by a double membrane which consists of a layer of sheet material 14 provided with a single hole 16 and a second member 18 which is porous. The upper chamber has metallic side walls 24) which are for the most part cylindrical but flare out toward the bottom at 22 where they meet and abut with rim 24 of cup shaped member 26 which forms the walls of chamber 12. The two barrier members 14 and 38 rest on the ledge provided by the rim 24 and are integrally sealed to the members 22 and 24 preferably by a welding operation. A glass bead 30 through which two electrodes 32 and 34 project inwardly into space 1d hermetically seals sintering conditions.

chamber 10 and keeps any gases from entering therein or permitting the mercury 36 which may be in either chamber 16 or. 12 from leaking out into the atmosphere. During the period in which this switch is stored the mercury is usually positioned in chamber 10 and serves to act as conductor between the electrodes 32 and 34.

Mercury unshorter switches embodying features of this invention could naturally be made of many types of materials and in various designs while still embodying these features. Essentially, it is merely important that the switch be made up in such manner as to have at least two chambers separated by a double barrier with the conducting medium as, for example, mercury positioned in the chamber or chambers. It is, of course, preferable that the materials from which such switch be made are not reactive with the conducting material so as neither to form non-conducting compounds or to form compounds or other substances which cannot pass through the barrier materials under the conditions under which they should operate or to otherwise plug up n e barrier material during the period of storage. The compound or material used should also not form a scum which will bridge the electrodes and keep them shorted even though most of the conductive material has passed through to chamber 12. These barrier members have, for example, been made of either solid one hole discs out of cold rolled steel or out of discs made by powder metallurgical processes in which the sintered disc is porous and has a controlled amount of porosity due to the grain size of the powder from which it is made as well as the compacting pressure and Such discs, however, will not stand up under the normal jolt and jumble test which is some indication as to how switches would stand up under the normal handling conditions to which they would be subjected, prior to their actually being put to the use intended.

In accordance with this invention it has been found, however, that when such a single disc is replaced by a double disc in which the one disc is spaced from the other by no more than .030 the switch is made joltproof.

The preferred design of the double disc of this type calls for as solid disc such as shown at 14 in FIGURE 1 stampedfrom either cold rolled steel or stainless steel sheet stock into which a recess 15 is drawn so that when a second disc is held adjacent thereto the one is spaced from the other by not more than .030". The optimum distance between these two discs is in the neighborhood of .002" to .006". The stamped disc is then provided with a single hole in the center as indicated in FIGURE 1 of the drawings at 16. This hole diameter is, of course, dependent upon the timing desired. For a switch in which mercury i to be used as the conducting medium and which is to be unshorted in 1 to 3 seconds when it is spun at revolutions per second or unshorted in a period of .12 to .22 second when spun at 260 revolutions per second a hole of diameter .0055" is satisfactory. The porous disc 18 is similar in size to the solid disc 14 and is provided with a dense annular ring 19 along its outer edge. Thi ring rim is formed by a coining operation after the remainder of the disc has been formed by compacting it flat and sintering the disc, or the dense rim may be made in the original compact and this rim subsequently densified further by coining after sintering. The dimensions of the porous disc may, of course, be altered to accommodate design changes in the switch. The porous disc can, of course, be made from many materials. When mercury is used as the conducting medium in the switch it has been found that stainless steel powders are particularly well suited for this purpose.

Since the switches are timing devices it is of course to be understood that the porous disc must be made uniformly if the switches are to have the proper timing action. When the two discs have been made they are assembled with the remaining components of the switch by being flash welded into the switch as shown above with the solid one hole disc adjacent to the chamber in which the mercury i to be stored. This chamber is in those cases in which the switch is used as an unshorter switch into which the electrodes protrude. A positioning of the solid disc facing this chamber is not critical in regard to timing of the switch but it is a critical factor when the switch is to pass a jolt and jumble test. The test closely resembles the condition of transportation or storage when the switch is not in actual use. In some actual tests it has been found that although the porous disc is more jolt-proof than the one hole disc neither it nor the one hole disc alone will prevent mercury from jolting through. However, when the combination is assembled as shown in FIGURE 1 of the drawing a pressure drop occurs in the mercury passing through the upper disc and the porous disc is sufliciently dense to prevent the mercury from flowing through.

A modification of the porous disc shown in FIGURE 1 is illustrated in FIGURE 2 of the drawings which shows a solid one hole disc 23 (of the same type as disc 14) in conjunction with a porous disc 25 in which a dense center 19 on the order of 0.1" in diameter is present. This area can be densified by coining alone during the coining of the rim or it can be made somewhat dense during compacting and further densified by coining after sintering. The purpose of this dense center is to aid in the prevention of mercury passage during jolt and jumble even though the mercury passing through both of these discs must necessarily pass through a circuitous route to pass into the lower chamber it as been found that such change in direction does not significantly change the timing of the switch.

A second modification is shown in FIGURE 3 of the drawings wherein the solid disc having the single hole is replaced by a second porous disc 21 (of the same type as disc 18). This leaves a structure with two porous discs 21 and 27 facing one another. This type of structure has also proven to be as satisfactory for certain special uses and will prevent the passage of mercury through the double diaphragm arrangement as long as the spacing between the two discs is maintained at less than .030". In all other respects this structure is similar to that shown in FIGURES 1 and 2 of the drawings and can be used for similar purposes.

While the above description and drawings submitted herewith disclose a preferred and practical embodiment of the switch of this invention it will be understood by the specific details of construction and arrangement of parts as shown and described are by way of illustration and are not to be construed as limiting the scope of the invention.

What is claimed is:

l. A mercury type switch having aplurality of cornpartments separated by a pair of spaced barrier members, a pair of spaced electrodes projecting into at least one compartment of said switch, and an electrical conducting fluid medium within the walls of said switch, said barrier members being made of the combination of a pressed and sintered porous metal disc and a solid disc containing an opening and being adapted to permit the passage of said electrical conducting fluid medium from one compartment to another under a definite pressure time relationship.

2. A mercury type switch having a plurality of compartments separated by a pair of spaced barrier members, a pair of spaced electrodes projecting into at least one compartment of said switch and an electrical conducting fluid medium within the walls of said switch, said barrier members comprising the combination of a solid disc with a single hole and a porous pressed and sintered disc and being adapted to permit the passage of the electrical conducting fluid medium from one compartment to another under a definite pressure time relationship.

3. A mercury type switch having a plurality of compartments separated by a pair of spaced barrier members, a pair of spaced electrodes projecting into at least one compartment of said switch and an electrical conducting fluid medium within the walls of said switch, said barrier members consisting of a pair of metal discs one of which is solid with a hole therein and the other of which is a porous pressed sintered metal body with a densified center section surrounded by an annular porous section and being adapted to permit the passage of the electrical conducting fluid medium from one compartment to another under a definite pressure time relationship.

4. A mercury type switch having a plurality of compartments separated by a pair of spaced barrier members, 7

a pair of spaced electrodes projecting into at least one compartment of said switch, and an electrical conducting fluid medium within the walls of said switch, said barrier members being made of two pressed and sintered porous metal discs at least one of which has a densified center section surrounded by an annular porous section adapted to permit the passage of said electrical conducting fluid medium from one compartment to another under a definite pressure time relationship.

5. A mercury type switch having a plurality of compartments separated by a pair of barrier members, spaced within the range of .002 and .006", a pair of spaced electrodes projecting into at least one compartment of said switch and an electrical conducting fluid medium within the walls of said switch, said barrier members-consisting of a pair of metal discs one of which is solid with a hole therein and the other of which is a porous pressed sintered body with a densified center section and being adapted to permit the passage of the electrical cutting fluid medium from one compartment to another under a definite pressure time relationship.

6. A mercury type switch having a plurality of compartments separated by a pair of barrier members spaced by no more than .030", a pair of spaced electrodes projecting into at least one compartment of said switch, and an electrical conducting fluid medium within the walls of said switch, said barrier members being made of two pressed and sintered porous metal discs at least one of which has a densified center section adapted to permit the passage of said electrical conducting fluid medium from one compartment to another under a definite pressure time relationship.

References Cited in the file of this patent UNITED STATES PATENTS Re. 20,099 Larson Sept. 8, 1936 Re. 20,100 Larson Sept. 8, 1936 1,162,516 Richmond Nov. 30, 1915 2,273,928 Brian Feb. 24, 1942 2,404,179 King July 16, 1946 2,414,836 Rickmeyer Jan. 28, 1947 2,436,601 Rickmeyer Feb. 24, 1948 

1. A MERCURY TYPE SWITCH HAVING A PLURALITY OF COMPARTMENTS SEPARATED BY A PAIR OF SPACED BARRIER MEMBERS, A PAIR OF SPACED ELECTRODES PROJECTING INTO AT LEAST ONE COMPARTMENT OF SAID SWITCH, AND AN ELECTRICAL CONDUCTING FLUID MEDIUM WITHIN THE WALLS OF SAID SWITCH, SAID BARRIER MEMBERS BEING MADE OF THE COMBINATION OF A PRESSED AND SINTERED POROUS METAL DISC AND A SOLID DISC CONTAINING AN OPENING AND BEING ADAPTED TO PERMIT THE PASSAGE OF SAID ELECTRICAL CONDUCTING FLUID MEDIUM FROM ONE COMPARTMENT TO ANOTHER UNDER A DEFINITE PRESSURE TIME RELATIONSHIP. 